Apparatus for the desiccation of organic substances



May 24, 1 49- F. E. HURD 2,471,035

APPARATUS. FOR THE DESICCATION OF ORGANIC SUBSTANCES Filed Oct. 2, 1943 Patented May 24, 1949 APPARATUS FOR THE DESICC'ATION F ORGANIC SUBSTANCES Frank E. Hurd, New York, N. Y.

Application October 2, 1943, Serial No. 504,794

4 Claims. 1

This invention relates in general to certain new and useful improvements in apparatus for the desiccation of organic substances and more particularly food products and the like.

Many organic substances and particularly food products which contain flavor producing esters, vitamins and various other readily decomposable compounds, are diflicult to desiccate and are frequently impaired in value by existing processes. Recently it has been proposed to freeze such products into crystalline form and desiccate them by sublimation of the water from the ice crystals under high vacuum leaving'a light, amorphous and extremely hygroscopic residue. Hitherto such processes of desiccation have been conducted on a batch basis and hence have been relatively expensive and time consuming. Furthermore it is difilcult to obtain a desirable volume of production by batch methods to meet the demands of many industries in which low temperature, high vacuum desiccation might otherwise find ready use.

It is therefore the primary object of this present invention to provide methods and apparatus for low temperature high vacuum desiccation which are substantially continuous in operation and result in substantial economies both in cost of original installation as well as operation and maintenance.

Numerous other objects, advantages and inherent functions of the invention will become apparent as the same is more fully understood from the following description which, taken with the accompanying drawing, discloses "a preferred form of the invention.

In the drawing:

The figure is a diagrammatic view of a preferred form of apparatus embodying the present invention.

Referring now in more detail and by reference characters to the drawings which illustrate a preferred embodiment of the present invention, I designates a suitable vessel or tank for storage of the organic liquid after it has been expressed, extracted, pasteurized or' otherwise prepared. Connected at its intake to the storage tank I by means of a pipe-line 2 is a pump 3 which is in turn connected on its discharge side to a pressure vessel 4, having a head space 3 and a preferably removable, gasketed head or cover 5 connected through a gas-line 6, reducing valve I, and pressure gage 8 to a cylinder 9 of some inert gas such as nitrogen or carbon dioxide. In this connection it should be pointed out that the use of an inert gas is optional and may be omitted in many cases. However, in the processing of vitamin-containing liquors such as fruit juices for instance it is considered good practice to tie-aerate the juice immediately after extraction and insuch cases the use of high pressure air in the pressure vessel would nullify the eflect of de-aeration. For these reasons it is preferable though not essentia that some inert gas be employed.

Opening into the lower portion of the pressure vessel 4 is a conduit or pipe-line I0 having a suitable control valve II and extending into a desiceating chamber I2 for connection with a spray" head I3 consisting of one or more atomizing nozzles M. The desiccating chamber I2 is connected at its upper end through a large diameter line I5 to a conventional vacuum pump (not shown) and is preferably provided with a jacket I6 and an enclosing layer ll of rock wool, asbestos or other suitable insulating material. The dimensions of the desiccating chamber l2'wi1l of course depend upon the desired quantity of production and the specific characteristics of the liquid being processed except'that it is desirable that the height be sufiicient so that the atomized particles issuing from the nozzles I I will not reach the bottom too quickly and the force of the blast from thenozzles will be substantially dissipated.

Formed integrally with or secured tightly to the spray-head I3 is a heat exchange coil I9 the ends of which extend outwardly through the walls of the desiccatingchamber I2 and are connected in closed circuit through a circulating pump 20 to a cooling worm 2| located within the pressure vessel 4. This closed system may be filled with brine, glycerine or other circulating coolant as specific conditions and requirements may demand. Similarly the jacket I6 is connected in closed circuit through a circulating pump 22 and a conventional temperature control unit 23, the latter being either in the form of a heater or refrigerator depending upon whether the particular conditions of operation will require heating or cooling of the desiccatin chamber I2. In fact for some types of operations the jacket I6 and insulation I1 may be omitted entirely since the heat absorbed from or dissipated. to the ambient atmosphere will be adequate to maintain desired temperature conditions within the desiccating chamber I2 as will presently more fully appear.

At its lower end the desiccating chamber I2 is provided with a downwardly converging hopper bottom 24, which is connected by a feeder pipe 25 to a conventional vacuum packaging machine 26. Depending upon the type of product being processed the packaging machine may be of a type designed to package the product in tin, glass or foil containers, whichever may be expedient.

In operation, the liquid such as fruit juice for instance is pumped from the storage tank I through pump 3 into the pressure vessel 4 and placed under substantial pressure. Meanwhile the pressure is reduced in the desiccating cham-- her to a vacuum of 29" or lower (all pressures are 3 given in inches of mercury). The valve II is then opened and the liquid permitted to atomize through the nozzles I 4. The extremely small globules of liquid will, when exposed to the high vacuum within the desiccating chamber l2, be rapidly chilled by the almost instantaneous evaporation of water and will freeze. The frozen particles will then fall down through the desiccatin chamber l2 and by the time they reach the hopper bottom 24 all of the water will have been sublimed. Of course the flow of liquid through valve II will at first be very small but within a relatively short time the rapidity of evaporation will reduce the temperature so much that the spray head l3 will become chilled. Thereupon the pump 20 is started up and the coolant circulated through the heat exchanger 19 and worm 2| thus chilling the liquid in the pressure vessel 4 and at the same time preventing the nozzles l4 from freezing up. The valve 1 l and-the pump 20 are regulated gradually so that the liquid in the pressure vessel 4 will be super-cooled, that isto say chilled to a temperature slightly below its normal freezing point. Inasmuch as the liquid is maintained under high pressure its freezing point will be lowered somewhat. This supercooled liquid will, when atomized, freeze instantly. By reason of the small size of the particles a relatively'great amount of surface area will be exposed for release of water vapor, and

. the resultant process of desiccation will be extremely efficient and rapid.

The desiccated material will collect in the hopper bottom 24 and be discharged through the feeder pipe 25 to the packaging machine 26.

If desirable or necessary for any given operation or specific product the cooling worm 2| and the heat exchange coil 19 may be respectively connected through conventional valves and pipe lines to a refrigerating unit 27 and heating unit 28 respectively as shown in dotted lines in Fig. 1. By such means it is possible to regulate the temperature of the spray independently of the cooling eifect created at the nozzles 14 and similarly it is possible to warm the nozzles l4 to any desired degree independently of the cooling worm 2|. It is also possible to start the apparatus using such independent temperature regulating means and at the proper moment by suitable adjustment of valves switch over to the self-cooling type of operation previously described.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that changes may be made in the form, construction, and arrangement of the several parts of the illustrated apparatus without departing from the spirit or scope of my invention or sacrificing any of its attendant advantages. For example, it is possible, in a given installation, to vary the height of the vacuum chamber, increase the temperature at which the liquid is introduced into the vacuum chamber, or employ very low pressures ranging down to the order of a few microns depending upon the specific product being processed.

I claim:

1. Apparatus for desiccating a, liquid which comprises a vessel for holding the liquid, a cooling worm in the vessel, a vacuum chamber, atomizing means within the chamber, means connecting the vessel with the atomizing means for conducting liquid from the vessel to the atomizatomizing means and means for circulating a coolant between said heat exchanger and the cooling worm for utilizing the cooling eflect produced at the atomizing means to cool the liquid in the vessel.

2. Apparatus for desiccating a liquid which comprises a vessel for holding the liquid, means for imposing pressure upon the liquid in the vessel, a cooling worm in the vessel, a, vacuum cham.. ber, atomizing means within the chamber, means connecting the vessel with the atomizing means for conducting liquid from the vessel to the atomizing means, a. heat exchanger associated with the atomizing means and means for circulating a coolant between said heat exchanger and the cooling worm for utilizing the cooling effect produced at the atomizing means to cool the liquid in the vessel.

3. Apparatus for desiccating a liquid which comprises a vessel for holding the liquid, means for imposing an inert gas under high pressure upon the liquid in the vessel, a cooling worm in the vessel, a vacuum chamber, atomizing means within the chamber, means connecting the vessel with the atomizing means for conducting liq uid from the vessel to the atomizing means, a heat exchanger associated with the atomizing means and means for circulating a coolant between said heat exchanger and the cooling worm for utilizing the cooling efiect produced at the atomizing means to cool the liquid in the vessel.

4. Apparatus for desiccating a liquid which comprises a vessel for holding a liquid, means for imposing pressure upon the liquid in the vessel, a cooling worm in the vessel, a vacuum chamber atomizing means within the chamber, means connecting the vessel with the atomizing means for conducting liquid from the vessel to the atomizing means, a heat exchanger associated with the atomizing means, and means for circulating a temperature controlling medium between the heat exchanger and the cooling worm.

FRANK E. HURD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,969 Reichel Jan. 3, 1939 875,405 Barse Dec. 31, 1907 996,832 Campbell July 4, 1911 999,707 Ellis Aug. 1, 1911 1,029,201 LeBlanc June 11, 1912 1,863,355 Schibsted June 14, 1932 1,884,429 Warner Oct. 25, 1932 2,100,151 Tietz Nov. 23, 1937 2,225,774 Flosdorf Dec. 24, 1940 2,303,021 Butty Nov. 24, 1942 2,345,548 Flosdorf et al. i Mar. 28, 1944 2,363,445 Shipstead et al Nov. 21, 1944 2,388,917 Hormel Nov. 13, 1945 2,390,167 Patrick et al Dec. 4, 1945 2,411,152 Folsom Nov. 19, 1946' FOREIGN PATENTS Number Country Date 15,231 Australia Sept. 3, 1929 840,092 France Jan. 11, 1939 539,477 Great Britain Sept. 12, 1941 

